What Function Does DNS Server Perform?


Larry Thompson

When you type a website’s URL into your browser, have you ever wondered how it knows where to go? That’s where the DNS server comes in.

What is a DNS server?

DNS, which stands for Domain Name System, is like the address book of the internet. It translates human-readable domain names, such as www.example.com, into IP addresses, which are a series of numbers that computers use to identify each other on the internet. Just like you would look up a contact’s name in your phone’s address book to find their phone number, your computer uses a DNS server to look up the IP address of a website you want to visit.

How does a DNS server work?

When you type a URL into your browser, it sends a request to your Internet Service Provider’s (ISP) DNS servers. These servers act as middlemen between your computer and the rest of the internet.

If the ISP’s DNS server has the IP address for the requested domain name cached (stored), it will return it directly to your computer. This caching system helps speed up future requests for that same domain name.

If the ISP’s DNS server doesn’t have the IP address cached, it will pass on your request to other DNS servers until it finds one that does have the information. This process is known as recursive querying since each server queries another until it finds an answer.

The importance of DNS

The DNS system plays a vital role in ensuring that websites load quickly and efficiently. Without it, we would need to remember long strings of numbers (IP addresses) instead of user-friendly domain names. Additionally, since websites often change their IP addresses or move servers, having a dynamic system like DNS allows these changes to be made easily without affecting users.

DNS records

In addition to translating domain names into IP addresses, DNS servers also store various types of records that provide additional information. Some common DNS record types include:

  • A (Address) record: Maps a domain name to an IP address.
  • CNAME (Canonical Name) record: Maps an alias (subdomain or www) to the canonical domain name.
  • MX (Mail Exchanger) record: Specifies the mail server responsible for handling email for a domain.
  • TXT (Text) record: Stores arbitrary text data associated with a domain.

These records help ensure that different services, such as email and web hosting, can be provided by different servers while still being associated with the same domain name.

DNS caching

To improve performance and reduce the load on DNS servers, DNS records have a Time-To-Live (TTL) value. This value specifies how long a DNS server should cache a particular record before checking for updated information. By caching records, subsequent requests for the same domain name can be resolved faster since the DNS server doesn’t need to query other servers again.


The DNS server is an essential component of how the internet works. It translates user-friendly domain names into IP addresses that computers can understand.

By doing so, it ensures that we can access websites easily and efficiently. Understanding how DNS works can help us troubleshoot issues and appreciate the complexity behind simple actions like typing a URL into our browsers.

So next time you visit a website, remember to thank the unsung hero behind-the-scenes – the DNS server!

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